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From "Fabian Hueske (JIRA)" <j...@apache.org>
Subject [jira] [Created] (FLINK-3944) Add optimization rules to reorder Cartesian products and joins
Date Fri, 20 May 2016 12:59:13 GMT
Fabian Hueske created FLINK-3944:

             Summary: Add optimization rules to reorder Cartesian products and joins
                 Key: FLINK-3944
                 URL: https://issues.apache.org/jira/browse/FLINK-3944
             Project: Flink
          Issue Type: Bug
          Components: Table API
    Affects Versions: 1.1.0
            Reporter: Fabian Hueske
            Priority: Critical
             Fix For: 1.1.0

Currently, we do not support the execution of Cartesian products. 
Because we do not optimize the order of joins (due to missing statistics), joins are executed
in the order in which they are specified. This works well for the Table API, however it can
be problematic in case of SQL queries where the order of tables in the FROM clause should
not matter.

In case of SQL queries, it can happen that the optimized plan contains Cartesian products
because joins are not reordered. If we add optimization rules that switch Cartesian products
and joins, such situations can be resolved.

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